Re: Grossly over exposed images during rapid shooting Canon Mk III

I think the mirror mechanism not moving full back into position is the most likely cause of your overexposure.

I'd send the camera into Canon for service and cleaning.

Mechanical failure can never be completely ruled out, but I think this issue is more operator error than mechanical failure. I just don't see the mirror sometimes working perfectly, and then occasionally not working, and then coming back to life.

This seems to be more of a metering issue, than a mechanical issue. If the mirror were a problem, wouldn't it show up in the viewfinder?

Re: Grossly over exposed images during rapid shooting Canon Mk III

Mechanical failure can never be completely ruled out, but I think this issue is more operator error than mechanical failure. I just don't see the mirror sometimes working perfectly, and then occasionally not working, and then coming back to life.

This seems to be more of a metering issue, than a mechanical issue. If the mirror were a problem, wouldn't it show up in the viewfinder?

Not if it is just momentarily sticking. Or perhaps now that he knows to watch for it he may notice the viewfinder blanking longer than normal.

If he has 2nd shot focus set to shot priority, the camera will just shoot away without worrying about the mirror coming back to obtain focus (or proper metering). I keep mine set to focus priority so it will slow the shot rate down slightly as it ensures focus between shots (which requires the mirrors to fully return to position).

Re: Grossly over exposed images during rapid shooting Canon Mk III

I think the mirror mechanism not moving full back into position is the most likely cause of your overexposure.

I'd send the camera into Canon for service and cleaning.

Mechanical failure can never be completely ruled out, but I think this issue is more operator error than mechanical failure. I just don't see the mirror sometimes working perfectly, and then occasionally not working, and then coming back to life.

This seems to be more of a metering issue, than a mechanical issue. If the mirror were a problem, wouldn't it show up in the viewfinder?

The other day, my wife, daughter, grandson, and I were riding in an excursion train, when a woman in our car offered to take a picture of the four of us. I handed her my 5D3, which was set to Av, 1/200, ISO 1250, with a forward pointing 600EX-RT in E-TTL mode. She ran off three quick shots (elapsed time of 2 seconds), and all three were grossly overexposed at f/3.2. I had taken a picture of my wife with the same settings two minutes earlier, and it was properly exposed at f/7.1.

The best hypothesis I could come up with was that maybe the woman had pressed the shutter button so fast that the camera hadn't had time to meter (and/or the flash hadn't had time to get its mind right), though the focus appeared OK. For the rest of the day and the next day, both with heavy use, the camera performed flawlessly, so the overexposures were definitely a fluke. Does my proposed explanation make any sense? And in any case, could what happened to me be causally similar to the events being pondered in this thread? (Note that I was not using auto-ISO.)

Re: Grossly over exposed images during rapid shooting Canon Mk III

Fully pressing the shutter too quickly can cause bad exposures and out-of-focus shots, especially if you are in AI Servo mode.

I gave one of my sons a T5 in 2014, and he used the shutter as if it were a cell phone. Punch it. I had to show him how to let the camera meter and focus by half-pressing the shutter. He said the camera wouldn't take a picture. He was using One Shot mode, Green [A].

He began using M, "monster" mode as he used to call it, and would get bad exposures shooting AI Servo. He had not yet discovered continuous shooting mode, and was punching the shutter again.

Re: Grossly over exposed images during rapid shooting Canon Mk III

Thank you all those who have contributed, I appreciate your views, comments and suggestions. I was hoping that someone in the forum would have come accross the same malfunction and advised how it was resolved. This camera is not 3 months old and the problem maybe unique. I don't believe it is an operator problem, I believe that since it is so new and that I have had this malfunction on a number of occasions, it is a mechanical fault, so I think it is an issue for Canon. So I shall close this dialogue, and report back once the problem has been resolved. Thanks.

Re: Grossly over exposed images during rapid shooting Canon Mk III

I too get the same problem occasionally. I have noticed it on my XT, and when I got my T5, the same thing. I just got a T6i in May and yup, same thing. Mine though is not as extreme as yours.

On Sunday I took three shots within a minute of a softball catcher with the T5. ISO fixed at 400, Aperture fixed at 8.0. On the first shot, the shutter was 640, the second, was 1000, and the last was 320. It was a lightly cloudy day and the shadows are very strong on each, suggesting no cloud cover.

Other times I done burst and seen similar deviations within the burst.